Dynamics of weakly coupled random antiferromagnetic quantum spin chains

TL;DR

This paper investigates the low-energy excitations and dynamical properties of weakly coupled disordered antiferromagnetic spin chains, revealing collective spin wave modes and their characteristics using advanced theoretical methods.

Contribution

It introduces a combined real-space renormalization group and RPA approach to analyze collective excitations in disordered coupled spin chains, connecting theory with experimental observations.

Findings

Support for collective spin wave excitations in disordered chains

Calculated spin wave velocity and spectral weight within RPA

Comparison with neutron scattering experiments on doped CuGeO3

Abstract

We study the low-energy collective excitations and dynamical response functions of weakly coupled random antiferromagnetic spin-1/2 chains. The interchain coupling leads to Neel order at low temperatures. We use the real-space renormalization group technique to tackle the intrachain couplings and treat the interchain couplings within the Random Phase Approximation (RPA). We show that the system supports collective spin wave excitations, and calculate the spin wave velocity and spectra weight within RPA. Comparisons will be made with inelastic neutron scattering experiments quasi-one-dimensional disordered spin systems such as doped CuGeO$_3$